In the related art, a microcomputer has been used in a control device, and a processorless hard-wired method that aims to improve security and tamper-resistance has been required in a control device that requires high security, for example, a control device of a large plant or a power generation facility. Meanwhile, maintainability has also been required to ensure an easy adjustment for each applicable device. To meet these requirements, an FPGA is beginning to be used for a control device. In particular, a Flash type FPGA having high soft error resistance is beginning to be used in a high-security control device in order to avoid a temporary failure in the control device and consequent breaking down due to a soft error caused by radiation such as neutrons.
As background art, JP-A-2005-249609 (PTL 1) describes “a security protection instrumentation system of a reactor which is constructed by using digital logic that is implemented in hardware selected from ASIC and FPGA, in which a digital logic section is constituted by using at least one of a function unit, in which output logic patterns corresponding to all input logic patterns are verified in advance in a pre-implementation stage, and a function module which is constituted by combining the verified function unit, and the function module is constituted only by a function unit having the same logic configuration as the verified function unit.”